Linksys NSS2000 Cisco NSS4000 and NSS6000 Series Network Storage System Admini - Page 67

Configuring your Storage Viewing the Snapshot Reserve Details 4 Viewing the Snapshot Reserve Details You can configure the NSS6000 series NAS to take snapshots of the data on an existing volume. When you create a snapshot, a backup of each of the shares on the volume is created and is available within the system's file directory to which end users of those shares have access. The advantage of a snapshot over a backup is that a snapshot is user-accessible and can be used for quick file recovery resulting from end-user error (such as an accidentally deleted file). A backup is only accessible to the administrator through the NSS configuration interface. Restoring data from a backup is generally a task that is scheduled with the IT administration staff. Backups are usually used to restore the system from a major system failure. Snapshots can be taken at various time intervals (such as hourly, daily, and so on). Each time a snapshot is taken, the previous snapshot is overwritten. You can also configure multiple snapshot sequences for the same volume. This is typically done to have snapshots occur at different time intervals. For example, you might want to capture a snapshot sequence for each hour, a separate sequence for weekly snapshots, and one for bi-weekly snapshots. In this case, the volume has three separate snapshot sequences. Each snapshot is overwritten when the next snapshot of the same frequency is taken. To ensure data integrity, during the creation of the snapshot (the duration is approximately a few seconds), no writes can occur to the share. The snapshot reserve is the amount of space that you want to allocate to the snapshot on the associated array. Once set, this space is not available for other storage use. The recommended amount of a reserve is generally between 10 to 20% of the total volume size. Note that if the period of time between snapshots is greater, the amount of the reserve should be greater. Or, if there is a heavy amount of activity on the volume, set a higher reserve. This is due to the snapshot reserve being used to store the changes to the volume contents since the last time the snapshot was taken. NOTE This feature is only available on the NSS6000. You cannot grow a volume if it is the target of a snapshot. If you want to grow such a volume, delete the snapshots first and then expand the volume. Linksys Small Business NSS4000 and NSS6000 Series Network Storage System Administration Guide 59